Liquid dispensers are well known and are in substantial commercial use. Such dispensers are utilized to deliver liquid soaps, hand lotions, creams, and the like. The key requirement for such dispensers is the ability to deliver metered amounts of product upon actuation of the dispenser without leakage from the dispensing tube, contamination, difficulty in cleaning or replacement of the liquid container, entrapment of air and other undesirable features.
A variety of dispensers are disclosed in U.S. Pat. Nos. 2,113,022, 3,066,832, 3,531,021, 3,741,439, 3,881,641, 4,228,930 and 4,350,268. For example, in U.S. Pat. No. 2,113,022 a spring driven arm with an attached roller is disclosed which squeezes liquid from a resilient tube. In fact, the general approach in a number of the prior art dispensers is to permit the liquid to flow into a flexible dispensing tube from a holding container and then to expel the liquid by pivoting a handle which in turn causes a roller mechanism to move along the tube toward the outlet to force the liquid through. A further representative system is disclosed in U.S. Pat. No. 3,741,439 wherein a lever with upstream and downstream portions is moved to wedge a portion of the tubing against a wall means, the upstream portion contacting the tube prior to the downstream portion so as to expel the liquid, and a closure means is utilized to prevent leakage from the tube.
The prior art dispensers have, however, exhibited one or more disadvantages. Such disadvantages include the need for substantial pressure to expel the liquid, difficulty in replacing the liquid reservoir, the handle pulling action serving to pull the dispenser from the mounting, liquid dripping, opportunity for bacterial contamination, the potential for entrapping air, difficulty in varying the volume of delivered liquid, inability to substantially empty the liquid reservoir, and the like.
It is, accordingly, the primary object of this invention to provide an improved dispenser for delivering viscous liquids.
It is a further object to provide a dispenser which substantially overcomes the disadvantages of the prior art dispensers particularly in the areas of exerted pressure, contamination potential and ease of operation.
It is another object to provide a unitary liquid reservoir and dispensing tube for use in the dispenser.
Various other objects and advantages of this invention will become apparent from the following description thereof.